1. Field of the Invention
The present invention relates to an input device which can perform a two-dimensional or three-dimensional input operation by moving a cursor on a screen for personal computers, entertainment systems, portable terminal units and the like. More specifically, the present invention relates to technologies allowing for downsizing, reduction in thickness of and improvement of the operating performance of an input device.
2. Description of the Related Art
Various input devices are known for display devices such as those for personal computers (hereinafter, such input devices will also be referred to as "pointing devices"). These pointing devices have various types of operating systems including a resistive pressure-sensitive system, a distortion system, an electrostatic capacitive system, and a membrane switch. However, each of these types of pointing devices has its own advantages and disadvantages, and no pointing device has been found which can simultaneously meet the requirements of excellent operating performance, reliability (environment resistance) and durability. Thus, a strong demand exists for a pointing device that can simultaneously meet these requirements.
In order to satisfy such a demand, the present applicant developed improved applications of optical pointing devices (Japanese Patent Applications Nos. 7-66071 and 7-161157).
The pointing device disclosed in Japanese Patent Application No. 7-66071 is a highly reliable and durable pointing device which can optically perform a two-dimensional input operation without requiring any contact for performing a detection. The pointing device is also excellent in operating performance because the pointing device uses an elastic structure made of rubber.
FIG. 34 schematically illustrates the detection principles of the pointing device. The pointing device includes: an operating portion 101 which is operated by the tip of a finger of an operator; a fixing portion 106; an elastic structure 102 for elastically supporting the operating portion 101 and for connecting the operating portion 101 and the fixing portion 106 to each other; a reflective plate 103 which is disposed on the lower surface of the operating portion 101; a single light-emitting element 104; four light-receiving elements 105; and a sensor portion which is fixed below the operating portion 101.
The light emitted upward from the light-emitting element 104 is reflected by the reflective plate 103 so as to be detected by the light-receiving elements 105. As shown in FIG. 34, when the operating portion 101 is moved to any of forward, backward, leftward and rightward directions, the position of the light (i.e., the location of the light spot) received by the light-receiving elements 105 is varied, so that the amounts of the light received by the four light-receiving elements 105, i.e., photodiodes PD1 to PD4, are also varied. The pointing device utilizes this principle for determining the direction and the amount of displacement of the operating portion 101, that is to say, the movement direction and the movement distance of a cursor 111 of a computer 110 or the like, in accordance with the equations shown in FIG. 34. In other words, this pointing device may function as an input device for the cursor 111.
On the other hand, the pointing device described in Japanese Patent Application No. 7-161157 is a pointing device which can perform a three-dimensional input operation. The pointing device can also perform a two-dimensional input operation (i.e., an operation performed in an X direction and a Y direction) by utilizing substantially the same configuration as that of the previously described pointing device. In performing the three-dimensional input operation, the pointing device calculates the movement amount of a cursor in a Z direction in accordance with the increase of the size of a spot of light received by the light-receiving elements when the operating portion is pushed downward. The size of the light spot is increased because the reflective plate 123 is also pushed down as the operating portion is pushed down, as shown in FIG. 35. In addition, since the increase of the size of the light spot varies the total amount of light to be detected by the four light-receiving elements, the pointing device can easily calculate the coordinate of the cursor in the Z direction.
Although the above input devices preform adequately, further improvements in operating performance reliability (environment resistance), durability and size reduction would be desirable.